Acoustic device



1935. r R. J. EMMERT 2,010,537

ACOUSTIC DEVICE Filed Nov. 10, 1950 3 Sheet-Sheet l Rafiezzjfmmeri.

g. 6, 1935. R. J. EMMERT 2, 1

ACOUSTIC DEVICE Filed Nov. 10, 1950 s Sheets-Sheet 2 Jwumtow 6, 1935- R. J. EMMERT 2,010,537

- ACOUSTIC DEVICE Filed Nov. 10, 1950 3 Sheets-Sheet 3 74 78 Rafienlfmmerf.

Patented Aug. 6, 1935 a H .REISSUED UNITED STATES PATENTOFFICE America, New York, N. Y., acorporation of Delaware 7 Application November 10,1930, Serial No. 494,646 1'Claim; (01. 179-1155) This invention relates to an acoustic device and centric with respect to the center pole piece durparticularly to an acoustic device having a frustoing the welding operation. conically shaped support having a conical or Another object of this invention is to improve frusto-conical diaphragm. upon the method of supporting the transformer. An object of this invention is to improve upon This has been accomplished by providing sup- '5 the methods of manufacture of the loud speaker porting ears integral with adjacent sides of adso as to produce a loud speaker that is substanjacent supporting arms of a diaphragm support tial, rigid, efiicient, and economical to produce. so that the transformer may be attached to said This has been accomplished by simplifying the ears.

0 construction by reducing the number of parts to "Another object of the invention is to place a 1 0- a minimum consistent with skilled workmanship, terminal board that is convenient and that rereducing the number of operations in the manuquires short leads. This has been accomplished facture of the speaker, reducing the amount of by placing the terminal board intermediate the labor required and reducing the cost by saving transformer and the supporting ears thereby re- 16 time, labor, and material. a

Another object of this. invention is 'to provide Further objects and advantages of the present a cone support made from sheet metal. This has invention will be apparent from the followin been accomplished by blanking a disc from a, piece description, reference being had to the accomof sheet metal, forming an annular channel near panying drawings, wherein a' preferred embodithe periphery of the disc, then blanking supportmenl? Of One form of the present invention is 20 ing members or arms from the centerof the disc d y wn. and forming these supporting members so as to In the aw gs! cause them to lie in a frusto-conical surface. 1 is o es a Sectional view taken sub- Another object of this invention is to improve stantially e ne l-l of Fig. 2 so as to disducing the length of the input leads. 1 5* upon the method of attaching'a diaphragm supclos the d ap agm Supporting disc. 25,

port to the magnetic frame. This has been ac- 2 is a p n V w of t cone supp t n complished by spot Welding the supporting arms disc before the center has been blanked and. of the support to the magnetic frame. formed in the Center: 7

Another object of this invention is to improve 3 115610568 the 16 supporting disc after upon the metallic frame. This has been accomplished by reinforcing the bottom of a cup-shaped housing for the metallic coil sothat there is a tendency to maintain a uniform flux density throughout the magnetic path.

' 'Fig. 4 discloses the cone support after the supporting arms have been extruded.

Fig. 5 discloses the cone frame structure assemgly without the cone the magnet and the Ano her ob'ec of this invention is to im re e 9 piece m position upon the annular pole piece so as to te d "to Flgvs disgoses the assembly after the electro' magnetic c011 and the pole piece have been asmaintain a substantially uniform flux density throughout the annular pole piece and so as to izfigig but before the centermg 31g has been has been accomplished by providing an. annular after complete-1y assemblei V pole piece constructed from two ferro-magneti'c Fig. 8 discloses a side View f a cone support annuluses, one of which has amaximumdiameter ho g a terminal block board in position equa to the maximum diameter of the c looking in the direction of the arrow 8 in Fig; 4.'

Another object of this invention is to improve tomary t fcrm the cone support from a, piece of upon the method of assembling the metallic sheetmetal by subjecting acircular disc provided ou This has been accomplished by welding with a. concentric pole into a frusto-conically the annular p l piece to the ped housing shaped support by a series of dies or forming the center has been blanked.

properly distribute the flux in the air This Fig. '7 discloses a sectional view of the speaker shaped housing. In the conventional speaker it has been cus- 4F so as to eliminate the conventional fastening; operations. This requires large heavy presses 501 means now used, such as screws or rivets. driven by a large motor consuming much power. Another object of this invention is to improve Consequently, these large presses arev expensive upon the method of centering the pole pieces. to install, occupy much space and are expensive This has been accomplished by providing a cento operate.

tering jig that holds the annular pole piece con- I have found that a suitable cone support Cir supporting a diaphragm of an acoustic device with respect to the electro-magnet may be made by severing a circular piece H] from a piece of sheet metal forming a channel l2 near the periphery ofjthe blank or, circular piece 10 as best seen in Figs. 1 and 2. r This may be done by means of a small press as the deformation of the channel I 2is relatively small. After this has been done the blank l0 provided with the annular channel I2 is placed in a stamping press that severs the blank along the lines l4, I6 and I 8 leaving the radial members or arms 29, 2|, 22 and 23. In the same operation the holes 24 are punched in the blank, the function of which will appear more clearly later. Asbest seen in Fig. 3 the supports 22 and 23 have been provided with ears or tabs 26, 28, 30 and 32 each of which has been provided with apertures .34. The function of these tabs and apertures will also appear more fully later.

After the blank has been thus formed it is placed in another die that extrudes the greater portion of the material found in the area inclosed by the channel I2 so that this center portion lies substantially in the surface of a frustoconical section. The innermost ends 36 of the radial supports 26, 2|, 22, and 23 lie substantially in the surface of a cylinder so as to snugly fit the outer periphery of the cup-shaped metallic housing 38. The tabs 36 of the radial supports 26, 2|, 22 and 23 are spot welded at 40 and 42 to the outer periphery of the cup-shaped housing 38. This is preferably done in a suitable jig that has not been disclosed for the reason that the jig does not form a part of the invention.

The magnetic housing 38 is provided with a center polepiece M riveted thereto at 46; The cross sectional area of the material used in the cup-shaped. housing 38 is just suificiently large so that there is substantially the same flux density in the walls of the housing as in the center pole piece 44. The reason for doing this is the desirability of using as light a material as possible so as to reduce. the cost of production and the weight of the magnetic housing. The cost of production is greatly reduced by an economical use of material andthe use of lighter.

material requires smaller presses, less power and lighter dies. j I

However, when this is done the flux densityof the bottom of the cup-shaped housing becomes too great in that the saturation point will be reached if a suitable flux density is maintained in the walls and the center pole piece. Consequently, in order to reduce the flux density in the bottom, a reinforcing plate 48 is placed on the bottom of the cup-shaped housing 38 so that the flux density will;notbecomeexcessive. A further advantage of the reinforcing plate 48 is to give an additional support to the-center pole piece 44 so thatthe bottom of the cup-shaped housing 38 is not as easily. deformed or bent out of shape when the speaker unit is jarred or jolted. w The assembly as seen in 5 is ready for receiving the magnetic coil, 56 which is inserted in the annular channel found I between the outer wall of thecup-shaped housing 38' and the center pole piece The annular pole piece 52 is provided with the reinforcinginember 54 that decreases the flux density near the air gap. 56 in much the same way as the reinforcing plate 48 1 decreasesthe flux density of the bottomjportion' of the cup sliap'ed'housingfiil; As the air gap 56 must be uniform throughout the annular recess or groove, a centering jig 5? is inserted between the annular pole piece 52 and the center pole piece 54 during the operation of welding the annular pole piece 52 to the cup-shaped housing. A packing washer 58 placed intermediate the coil 50 and the annular pole piece 52 retains the coil 56 in the position as disclosed in Fig. 6. The annular pole piece 52 is spot welded to the housing 38 in preferably three or four places throughout its perimeter.

, It can readily be seen that the support ill for the diaphragm, the cup-shaped housing 38, the reinforcing plate 48, the center pole piece M, the electromagnetic coil 59, the packing washer 58, and the annular pole piece 52 are all held in a relatively fixed relation as there is no chance for any relative movement between these parts without a failure in the material. Thus it is seen that a speaker assembly has been made that requires few parts, is light and rigid and is economical in cost.

The assembly shown in Fig. 6 is now ready for the frusto-conical diaphragm 5i! and the mounting of the transformer 62. The conical diaphragm 6B in this particular modification includes a flexible member 6 5, a centering spider 65, a speech coil support 68 and a speech coil winding H5. The diaphragm assembly 69 has a flexible band or rim fi l clamped intermediate the clamping member '!2 and the cone support I l. The flexible band 6 2, the cone support i l and the clamping member 72 are held in position by means of the screws M passing through each of these members.

As the diaphragm is made from fibrous material it is necessary to provide an additional support for the apex of the cone. This has been accomplished by passing a screw is through the spider 66 into a threaded aperture if; in the center pole piece 46.

A terminal block or board 3i! carrying suitable terminals for the leads 32 and 86 extending from the coil 50 is attached to the support by either screws 92 and 94 or other suitable fasteners passing through the holes E l in the ears 2%, 28, 3E: and 32 that are integral with adjacent supporting arms 22 and 23. Likewise the leads 86, only one of which is shown, extending from the speech coil '10, are attached to the terminal board 89 at 83. A transformer 62 is carried by the terminal board 8i] and rigidly held thereon by the screws 92and 94.

While the form of embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claim which follows.

What is claimed is as follows:

A loudspeaker comprising a diaphragm, a magnet structure including a cup-shaped magnet member, a supporting member for supporting the peripheral edge of thediaphragm, said supporting m mber including an annular portion positioned adjacent the peripheral edge of said diaphragm and a plurality of arms integral with said an nular portion, upturned portions at the free ends of said arms, means for securing said upturned portions to said cup-shaped member, a transformer supporting member, and a plurality of lugs on two of said arm portions for supporting said transformer supporting member.

' RODGER J. EMMERT. 

